Simone de Beauvoir and Jean-Paul Sartre were considered by many to be the perfect intellectual couple. They did not allow themselves to be constrained by social norms and went their own way, both in love and in their thinking about the world. ‘Man was to be remoulded, and the process would be partly our doing’, wrote the young Beauvoir about the beginning of her relationship with Sartre in Paris at the end of the 1920s. Still, experimenting with a different way of life not only brought ‘radical freedom’, but also painful deception and cruel candour, as their letters attest. ‘They were the transcription of immediate life’, acknowledged Sartre, whose letters from the front bear witness to a dark chapter in world history.